Ferrite toroid motors are a form of brushless D.C. motor and are fully described in U.S. Pat. No. 4,605,874, assigned to the assignee hereof, the disclosure of which is incorporated herein by reference. In such D.C. motors, a permanent magnet rotor has a plurality of magnetic poles and a stator bearing windings arranged to interact with the magnetic field produced by the magnetic poles to produce torque from D.C. current applied to the windings.
In one embodiment, the motor comprises a disk-like rotor element comprising a hard ferrite toroid providing a plurality of magnetic poles of alternating polarity and mounted for rotation about its axis and a disk-like stator element comprising a soft ferrite toroid and mounted coaxially with and spaced apart from the rotor. The soft ferrite toroid is formed with radially-directed coil winding receiving slots. Electrical coil windings are mounted to the stator element in the slots and each spanning one rotor pole pitch. The number of the radially directed coil winding receiving slots are a multiple of the number of magnetic poles of the rotor element. The electrical coil windings are series connected in the same multiple number of circuits which overlap each other in the winding slots. In one preferred embodiment of this motor, the motor has two circuits of stator windings and the stator has twice the number of poles present in the rotor.